VNS3 is a cloud-based networking and security platform designed for public, private, and hybrid environments, with over 1,200 customers. It offers various features like data encryption, overlay networking, and customizable network services, unlike OpenSwan, which is a free, open-source IPsec implementation with limited functionalities. VNS3’s pricing is subscription-based and caters to different use cases, while OpenSwan lacks enterprise support and advanced features.